This is a post that has been floating around in my head for a while, caused by many decisions I have seen in the businesses in which I have worked (mostly with regard to software purchases, but the idea can be generalised). I will start with defining the idea of a devil’s advocate and then move on to where I think it has a place in the modern business world. In my view the idea is also closely related to that of the 10th man rule (made famous by World War Z).